PROJECT SUMMARY/ABSTRACT Jamie L. Jackson, PhD, is an Assistant Professor in the Center for Biobehavioral Health at Nationwide Children?s Hospital and Ohio State University. Her career goal is to become an independent clinician-scientist with expertise in developing and implementing randomized behavioral clinical trials to improve self- management among transition-aged survivors of congenital heart disease (CHD). Dr. Jackson received a K23 award to examine the feasibility and preliminary efficacy of a physical activity (PA) intervention to increase moderate to vigorous PA engagement among adolescents with CHD. As CHD survivors enter adulthood, they have a greater risk for developing acquired cardiovascular complications, such as hypertension, coronary artery disease, and heart failure. These comorbidities are amenable to lifestyle changes, such as increasing PA. Rates of PA among emerging adults with CHD in the U.S. are relatively unknown, but rates in the general population decline during emerging adulthood. Therefore, for successful primary prevention of acquired cardiovascular complications in this growing population of aging CHD survivors, both adolescence and emerging adulthood may be optimal developmental stages to target for health behavior interventions. Given that emerging adulthood is a unique developmental stage, the feasibility of a PA intervention cannot be assumed and must be empirically determined. The proposed Small Grant Program for NHLBI K Recipients (R03) aims to 1) evaluate the feasibility of the same PA intervention being conducted as part of Dr. Jackson?s K23 award among emerging adult CHD survivors and 2) obtain qualitative feedback from participants on the content of the intervention sessions and study procedures using focus groups. Participants will include 30 emerging adults (ages 19-25) with critical CHD who will be randomized to 1 of 2 arms: a 20-week videoconferencing-administered PA intervention arm (8, 30 min sessions; tracking activity and setting goals using Fitbit) or a comparison arm that receives a Fitbit, but has no contact with a study interventionist. The Theory of Planned Behavior underpins the intervention content such that attitudes, normative beliefs, and perceived behavioral control will be addressed. Participants randomized to the intervention arm will be invited to participate in a focus group to provide further feedback. Objective and self-report measures of feasibility will be collected, including recruitment rate, adherence to intervention sessions, retention rate, assessment completion rate, and self-report of the intervention experience. Qualitative feedback will be audio recorded, transcribed, and coded. In addition to contributing to Dr. Jackson?s independence as a clinician-scientist, the results of the current study are expected to enhance the competitiveness of and inform the procedures for a larger R01 study, which will establish efficacy and determine the long-term effects of this intervention among transition-aged CHD survivors.